Jack’s Husky Infused 440/460 Hybrid

[drf256]

This is @Jchin build. @RI Chevy , don’t be upset by this build.

Worksaw Build, again.

The basis of this build is using a 52mm Husky 272 Meteor piston. It’s a lighter, single thick ringed piston that’s lighter than an 046 Meteor piston. It’s approximately .100 taller though, so some machine work is needed. It allows finger/boost ports if needed at a later date because of its central ring pin design. No fingers on a hybrid though, it’s got enough area to transfer its case volume.

Here’s the 272 vs 046 piston. The 272 is lighter, has bigger windows, and takes up less case volume. Was gonna try a 288 piston in a BB460 AM head, but the 288 pistons weight was prohibitive, and that’s without the 13mm pin for which I have no lighter replacement.
272

288

046

 

[drf256]

The 272 slug has a .140 distance from the ring to to the crown. It’s also the thickness of the crown when I measured it.

I took .040 off the crown to leave a safe .100 of thickness before the ring.

The blue line on the piston is the intake rook at BDC. The ring is comfortably covered.

Timing with 2 metal base gaskets is 107.5 Ex and 73 int with the cut piston stock.

It reduced weight to 72 grams. The Dominant saws titanium 12mm pin fit this piston comfortably tighter than the 046 slug for some reason. Plus, I’ve come to learn that they are intentionally undersized because they expand more than steel.

This saw will come apart for inspection after a few tanks. I’ll post some piston pics as well as a pic of the titanium pin after use.

So I’m around 20 grams lighter than an 046 Meteor and pin. The meteor does have wider skirts than the 272 piston though.

Anyone wanna weigh a 440/044 piston and pin for me? Also a 46mm x 1.4 caber vs. 2 46 x 1.2 cabers?

 

[drf256]

The goal for this build was a saw Jack could start. I intentionally needed to keep compression down. Because I needed to take 35 from the band to make the piston crown fit, I cut the chamber up .275 in at a 45* angle .200 deep with the compound and the boring bar. Band to bore area around 50%. Wound up with 152 psi at the end. Was gonna add a MacCullogh “T-slot” to the exhaust roof, but at 152 psi and with a new Husky 390XP decomp valve, it’s a 2 finger starter right now. If Jack isn’t comfortable with the starting, I can still change it.

 

[drf256]

Advanced timing 25 off the key. Had to use 2 base gaskets for clearance. Added a GenII @Red97 large deflector to the muffler after matching it to the Ex port.

The flywheel didn’t need to be clearances because the jug sat higher on the base. Only needed a drop off of the side tunnel for comfortable clearance.

Found a bad fuel line, that’s replaced. Some switch problems will be figured out today. Couldn’t find the damn NLA HD11 I wanted to use on the saw, so it’s got a 17B on it now.

Hope to run today if the rain holds out.

Final squish is at .022.

 

[drf256]

After a few runs, I’m gonna put the 461 HD50 on the saw. I’ll see if it wakes it up.

With the reduced reciprocating weight, I’m hoping she’s a runner.

 

[drf256]

Some more random pics of the build.

The jug is a Mahle low hour jug I got because of some broken fins. I repaired them, not the greatest, but functional repair. The plating is nearly new inside.

 

[XP_Slinger]

Great looking work Doc, love the technical detail in your builds. Looking forward to hearing this one rip

 

[traffic903]

Loving this build.

 

[72thing]

Nice work as usual, doc. Way to think outside the box.

 

[trooney]

I didn't know you could get that technical...hehe

 

[72thing]

The piston and pin removed from my MS440, minus rings.

I made a mad dash to my shop thru the rain. In my drawers, rubber boots, and raincoat.

Wanted to contribute something, lol.

 

[huskyboy]

Will a titanium pin wear as good as a normal one in the long run? Just the wheels turning in my head wondering. Nice work Al, looking foward to the video.

 

[Stump Shot]

Looking good Doc. I'm going to be trying a Meteor windowed 266 piston in my 044/440 build. Not so much for the savings of weight aspect, more for design options not possible with the factory piston.
Not sure my scale is small enough for weighing but if it will I'll weigh a 440 piston and pin and report back.

 

[Time's Standing Stihl]

Why you so worried about weight if it's just a worksaw?

 

[huskyboy]

Why you so worried about weight if it's just a worksaw?

Maybe less stress on the crankshaft in the long run/better throttle response? I’m not an engineer so that’s all I can guess.

 

[Deets066]

Why you so worried about weight if it's just a worksaw?

I was talking with Al a bit while he was workin on this saw. I don't believe that he's "worried" about the weight. Just pleased with how much lighter it turned out.

 

[Backtroller]

I’m sure that with the end goal of low compression so that the guy can start it, Jack is still wanting a saw that rips. Light weight intervals will help to add to the zip.

Cool build

 

[GCJenks204]

Why you so worried about weight if it's just a worksaw?

I may be speaking out of turn but I think Al said in the "What's on your Bench" thread that is was to help with making it easier to start.

I love the idea of a build that is fully designed around who the end user will be. Awesome work as usual Al.

 

[Duane(Pa)]

The piston and pin removed from my MS440, minus rings.

I made a mad dash to my shop thru the rain. In my drawers, rubber boots, and raincoat.

Wanted to contribute something, lol.

View attachment 109255

Oh... Thanks!

 

[drf256]

I was talking with Al a bit while he was workin on this saw. I don't believe that he's "worried" about the weight. Just pleased with how much lighter it turned out.

Yup

Not worried at all. Experimenting, bonus was reduced weight, which cant be bad.

It may not be worth the extra work, but one gains nothing from never trying.

Will be tough to tell how much of what works in this build. The compression is 30-50 psi lower than other builds of Hybrid 044/46. That may cause a torque loss, but a decreased parasitic loss as well.

I hope to see how it runs in a few hours time, if the weather cooperates.